Joe Mauer’s Batting Title Average — An Ephemeral Stat

[Update: Joe Mauer now qualifies for the batting title — this post is now irrelevant.]

Under the “Tony Gwynn Rule” Joe Mauer just took the batting title lead.

Apply the batting title criteria to Joe Mauer’s stats and Joe took the lead for the batting crown over the weekend, capped by his 3 for 5 performance against the Cubs on Sunday. Joe doesn’t have the “qualifying” plate appearances – but you don’t need all those PA’s to truly qualify, you just pay a major penalty if you’re short.

Call it the “Tony Gwynn” rule, if you will. The rule has been around since 1967, but it was Tony who benefitted from the rule in 1996 — a season where he ended up 5 plate appearances short of the batting title threshold of 3.1 plate appearances per game.

Tony’s season ending average was .353, ahead of Ellis Burks’ .344. Ellis had the highest batting average of any National Leaguer who qualified for the batting title. Did he take home the batting crown? No. The rule allows for trading in a player’s deficient PA’s for outs. Apply a theoretical zero-for-five day to Tony’s stats to get him to 503,* and Tony’s batting average would have been .349, keeping him ahead of Ellis.

* Most use 502 as the qualifying PA’s, but I come up with 503 using my canons of construction to interpret the horribly worded Official Major League Rule 10.22(a). The rule establishes a “minimum” of “as many or more total appearances at the plate” “as the number of games scheduled” multiplied by 3.1. The rule includes an example, which misses in its attempt to add clarity. The example reads: “If a major league schedules 162 games for each club, 502 plate appearances qualify (162 times 3.1 equals 502)” (emphasis mine).

162 times 3.1 does not equal 502. It equals 502.2. If 502.2 is a “minimum” then 503 is the first integer above the minimum. When interpreting a statute, I would look to the text for the meaning, and give little credit to an illustration with loose math.

Tony’s official batting average that year remained at .353, of course, but what if Ellis had hit .350? Tony would have appeared second on the batting title list with a .353 average, confusing future stat gazers who would see a .350 ranking higher on the list. I’ll do what any baseball geek does when he wants to minimize confusion — I’ll create a new stat (yeah, right). Tony’s batting average that year was .353, but his “Batting Title Average” (BTA) was .349.

As of close of business today (Sunday, June 14, 2009), Joe Mauer’s batting average is .413. His 181 plate appearances leave him 21 short of the 202 necessary for the Twins’ 65 games to date. Adding a hypothetical O-fer 21 streak to Joe’s season gives him a .364 BTA. Ichiro has a batting average (if you’re above the minimum, your BTA and BA are the same) of .360 as I type this. A season-ending strike breaks out overnight and Joe is the champion.

The batting leader lists of MLB, ESPN, et al. won’t bother to adjust for this dynamic during the season. There’d be too much ‘splainin’ to do. I doubt I’ll have the time to update this chart during the next few weeks until Joe catches up and it just won’t matter anymore. But here it is, shown below in a chart — a moment in the season when there is a secret champion.

2009 AL BTA Leaders as of the date below plus the top 2 in the 1996 NL race.

UPDATE: [Observation about Batting Title Average : If Joe Mauer sits a game, his batting average stays the same, but his Batting Title Average drops (an assumed 0 for 3.1). ]